Control apparatus



1966 G. A. VINCENT 3,264,605

CONTROL APPARATUS Filed Dec. '7, 1964 FIG. 2

FIG.|

GORDON A. VINCENT BY ATTORNEY nite State This invention pertains to improvements in electromechanical transducers and more particularly to improved compliant tubes for use therein.

Compliant tubes are generally constructed of some semiflexible material such as thin aluminum or fiberglass and are filled with a gas such as air so as to be relatively compressible. In use they are exposed to the liquid in which the transducer operates so as to provide a pressure relief or to control the effective compressibility of the liquid. A more detailed description of the prior art compliant tubes may be found in the A. W. Elston et al. Patent 3,127,527 assigned to the assignee of the present invention, in the W. J. Toulis Patent 3,021,504, and in a copending application of A. W. Elston and Gordon A. Vincent Serial No. 156,409, filed December 1, 1961, now Patent No. 3,241,099, and assigned to the same assignee as the present invention.

As the transducer is lowered into the water, the pressure on the compliant tubes increases. The gas-fllled tubes compress or deform to relieve the pressure, the amount of deformation being directly dependent on the external hydrostatic pressure. Since the pressure increases as the depth increases, the prior art gas-fil1ed compliant tubes encountered a maximum depth beyond which the compliant tubes would not be able to sustain the pressures encountered and would rupture. The obvious solution to this problem would he never to lower the transducer beyond this maximum depth. Nevertheless, it is often necessary to operate the transducer at or near maximum depth and occasionally an accidental lowering to too great a depth occurs. In such cases, the compliant tubes are frequently damaged or destroyed. For some requirements it may be necessary to intentionally lower the transducer below the normal maximum depth for short periods of time and it has become desirable to provide a compliant tube which can withstand a normally destructive pressure while maintaining its compressi-bility at normal depths.

Briefly, compliant tubes constructed in accordance with the present invention are protected from damage due to excess pressures by partially filling them with a noncompressible fluid. As the pressure on the compliant tubes increases the tubes deform or compress in a normal way and the volume within the tube decreases. At the maximum depth for which the tube is designed, the volume will be some predetermined minimum. Therefore, the volume of the noncompressible fluid partially filling the tube is made to be substantially equal to or slightly greater than this predetermined minimum volume. Thus, at normal depths and until the maximum pressure that can be normally withstood by the tubes is reached, the tubes operate in a normal manner since the compressible gas allows them to deform. Once the maximum pressure is reached, however, the gas is fully compressed and the noncompressible fluid substantially fills the entire volume within the tube. Further pressure increase only acts against the unyielding noncompressible fluid and the tube will not further distort, thereby protecting it from damage. In one embodiment of this invention the noncompressible fluid used was oil, but other fluids have been used with satisfactory results. The particular fluid is not critical for the practice of this invention as long as that fluid is substantially noncompressible.

It is an object of this invention, therefore, to provide an improved compliant tube for use in a transducer.

3,264,fl5 Patented August 2, 1966 It is another object of this invention to provide an improved compliant tube that will not be destroyed by excessive pressures.

These and other objects of this invention will become evident upon a reading of this specification and the appended claims in conjunction with the attached drawings of which:

FIGURE 1 is a sectional view of a compliant tube constructed in accordance with this invention.

FIGURE 2 is a cross-sectional view of a compliant tube taken along the line 22 of FIGURE 1.

FIGURE 3 is a cross-sectional view of a deformed or compressed prior art compliant tube.

FIGURE 4 is a cross-sectional view of a deformed or compressed compliant tube constructed in accordance with this invention.

FIGURE 5 is a sectional view of a portion of a compliant tube showing an alternative method of sealing the end of the tube.

Referring now to FIGURES 1 and 2, there is shown a compliant tube generally designated as 10. The tube is shown as being metallic, but the particular material used to construct the tube is not critical, provided the tube is semiflexible and rigid enough to withstand considerable pressure, yet flexible enough to deform or compress in response to the pressures encountered in operation. One example of another material that could be used is fiberglass. Other materials will be evident to those skilled in the art. The tube 10 is fitted with plugs or caps 12 and 14 which are sealed or bonded onto the ends of the tube It) to prevent transfer of fluid between the inside and outside of the tube. The geometrical shape of the cross-section of the tube when unstressed may be 0 shaped as is shown in FIGURE 2 but this configuration is arbitrary. The specific structure shown in FIGURES 1 and 2 consists of convex end portions 16 and 18 joined by straight side portions 20 and 22. The cross-section may also be elliptical or of some other shape if desired.

The void or space inside the tube 10 is filled with two fluids 24 and 26. Fluid 24 is a compressible gas as was used in the prior art compliant tubes and fluid 26 is a noncompressible fluid such as oil. As was explained hereinbefore, the particular fluid 26 is not necessarily oil, but can be any desired or convenient fluid as long as it is relatively noncompressible.

Referring now to FIGURE 3, there is shown the crosssection of a stressed or deformed prior art compliant tube 24, as it would appear after being lowered to some depth in the liquid surrounding it. The sides 26 and 28 are forced inward due to the pressure exerted by the medium surrounding the tube. The pressure exerted on the tube 24 also draws the curved or convex edges 30 and 32 into a smaller arc. Under these conditions, any additional pressure exerted on the tube 24 will force the edges 30 and 32 into an even smaller arc which may cause them to rupture so that the tube collapses and becomes useless.

Referring now to FIGURE 4, there is shown a crosssectional view of a stressed or deformed complaint tube constructed in accordance with the present invention. The sides 20 and 22 are forced inward due to the pressure exerted on the tube. The convex edges 16 and 18 are drawn into a smaller arc than when the tube is unstressed, but it is now seen that the noncompressible fluid 26 substantially fills the tube so that any increased external pressure will not further distort the tube.

Referring now to FIGURE 5, there is shown an alternative method of sealing the open ends of the tube. The sides 20 and 22 are squeezed or pinched together and Welded with a weld 34. Another alternative method of closing the ends of the tube that can be used if the tube '3 is not too large, is to simply weld the entire end shut without pinching the sides 20 and 22 together.

In operation, as the transducer is lowered into the liquid, the pressure on the tube 10 increases and the volume of the inside of the tube 10 decreases because the sides 20 and 22 are forced inward toward one another. As the volume inside the tube 10 decreases, the gas 24 is compressed allowing the tube to operate substantially the same as the prior art tubes. At some predetermined depth a maximum external pressure is reached and the volume of the tube 10 will be such size that substantially all of the space inside the tube 10 will be occupied by the noncompressible fluid 26. The fluid 26 will then restrain the tube from deforming further in case of accidental or intentional lowering of the transducer and will thereby prevent damage to the tube due to excessive pressures.

It is to be understood that while I have shown a specific embodiment of my invention that it is for illustration purposes only. Modifications and variations of the specific embodiment shown will be obvious to those skilled in the art. I intend that my invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. Compliant tube apparatus for use in electromechanical transducers comprising, in combination:

compliant tube means; noncompressible fluid means filling said compliant tube means to a predetermined fraction of the volume enclosed by said compliant tube means; and

compressible fluid means filling the remainder of said volume whereby said compliant tube means compresses in response to externally applied pressure thereby reducing the volume enclosed with said compliant tube means, said noncornpressible fluid means operating to limit the amount of compression of said compliant tube means thereby preventing damage to said compliant tube means.

2. Apparatus for use in transducers comprising, in combination:

compliant tube means operable to compress in response to externally applied pressures; and

substantially noncompressible fluid means partly filling said compliant tube means to a predetermined fraction of the volume enclosed by said compliant tube means.

3, Apparatus for use in transducers immersed in a fluid comprising, in combination:

sealed compliant tube means operable to increase the effective compressibility of the surrounding fluid;

first and second fluid means filling said compliant tube means, said first fluid means comprising a relatively compressible fluid, and said second fluid means comprised of a relatively noncompressible fluid thereby limiting the amount of compression of said compliant tube means.

4. Apparatus for use in a transducer normally operable within a first range of external pressure but which is protected from rupture when exposed to pressure in excess of the first range comprising:

a sealed compliant tube partly filled with a substantially noncompressible fluid.

5. Apparatus for use in transducers comprising:

a sealed compliant container partly filled with a noncompressible fluid and partly filled with a compressible fluid, said noncompressible fluid operable to limit the compression of said compliant container.

6. The method of protecting a compliant tube fro-m a rupture at excessive external pressure comprising:

partly filling the compliant tube with a substantially noncompressible fluid.

References Cited by the Examiner UNITED STATES PATENTS 2,592,134 4/1952 Firestone.

2,648,837 8/1953 Mounce 34012 X 2,906,993 9/1959 Steinberger 340-10 3,014,198 12/1961 Harris 340-8 3,021,504 2/1962 Toulis 340 s 3,127,527 3/1964 Elston 3401O CHESTER L. JUSTUS, Primary Examiner.

G. M. FISHER, Assistant Examiner. 

1. COMPLIANT TUBE APPARATUS FOR USE IN ELECTROMECHANICAL TRANSDUCERS COMPRISING, IN COMBINATION: COMPLIANT TUBE MEANS; NONCOMPRESSIBLE FLUID MEANS FILLING SAID COMPLIANT TUBE MEANS TO A PREDETERMINED FRACTION OF THE VOLUME ENCLOSED BY SAID COMPLIANT TUBE MEANS; AND COMPRESSIBLE FLUID MEANS FILLING THE REMAINDER OF SAID VOLUME WHEREBY SAID COMPLIANT TUBE MEANS COMPRESSES IN RESPONSE EXTERNALLY APPLIED PRESSURE THEREBY REDUCING THE VOLUME ENCLOSED WITH SAID COMPLIANT TUBE MEANS, SAID NONCOMPRESSIBLE FLUID MEANS OPERATING TO LIMIT THE AMOUNT OF COMPRESSION OF SAID COMPLIANT TUBE MEANS THEREBY PREVENTING DAMAGE TO SAID COMPLIANT TUBE MEANS. 